1st Abstract
| Title (1st Abstract) | Magnetic fields in Supernova Remnants and Pulsar-Wind Nebulae: Deductions from X-ray Observations |
| First Author | Stephen P. Reynolds |
| Affiliation | North Carolina State University |
| Presentation options | |
| Session | 4. Magnetic fields in SNRs and PWNe |
| 1st Abstract | Magnetic field strengths $B$ in synchrotron sources are notoriously difficult to measure. Simple arguments such as equipartition of energy can give values for which the total energy is a minimum, but there is no guarantee that Nature obeys it, or even if so, what particle population (just electrons? electrons plus ions?) should have an energy density comparable to that in magnetic field. However, the operation of synchrotron losses can provide additional information, if those losses are manifested in the synchrotron spectra as steepenings of the spectral-energy distribution above some characteristic frequency often called a “break” (though it is more typically a gradual curvature). A source of known age, if it has been accelerating particles continuously, will have such a break above the energy at which particle radiative lifetimes equal the source age, and this can give $B$. However, in spatially resolved sources such as supernova remnants (SNRs) and pulsar-wind nebulae (PWNe), systematic advection of particles, if at a known rate, gives a second measure of particle age to compare with radiative lifetimes. In most young SNRs, synchrotron X-rays make a contribution to the X-ray spectrum, and are usually found in “thin rims” at the remnant edges. If the rims are thin in the radial direction due to electron energy losses, a magnetic-field strength can be estimated. I present recent modeling of this process, along with models in which rims are thin due to decay of magnetic turbulence, and apply them to the remnants of SN 1006 and Tycho. In PWNe, outflows of relativistic plasma behind the pulsar wind termination shock are likely quite inhomogeneous, so magnetic-field estimates based on source lifetimes and assuming spatial uniformity can give misleading values for $B$. I shall discuss inhomogeneous PWN models and the effects they can have on $B$ estimates. |
2nd Abstract
| Title (2nd abstract) | Asymmetric Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3 |
| First Author (2nd abstract) | Stephen Reynolds |
| Affiliation (2nd abstract) | North Carolina State University |
| Additional Authors (2nd abstract) | Kazimierz Borkowski, Peter Gwynne, David Green, Una Hwang, Robert Petre, Rebecca Willett |
| Presentation options (2nd abstract) | |
| Session (2nd abstract) | 10. SNe and SNRs with circumstellar interactions |
| 2nd Abstract | The youngest Galactic supernova remnant (SNR) G1.9+0.3, produced by a (probable) Type Ia SN that exploded around CE 1900, is strongly asymmetric at radio wavelengths, with a single bright maximum in its shell, but exhibits a bilaterally symmetric morphology in X-rays. It has been difficult to understand the origin of these contrasting morphologies. We present the results of expansion measurements of G1.9+0.3 that illuminate the origin of the radio asymmetry. These measurements are based on a comparison of our 2015 400-ks Chandra |
Account
| First Name | Steve |
| Last Name | Reynolds |
| Institution | North Carolina State University |
| Country | USA |